Knapsack for a motorcycle sissy bar



FIG. 1 is a front elevational view of a knapsack for a motorcycle sissy bar showing our new design;

FIG. 2 is a rear elevational view;

FIG. 3 is a left side elevational view;

FIG. 4 is a top plan view; and

FIG. 5 is a bottom plan view. 

The ornamental design for knapsack for a motorcycle sissy bar, substantially as shown and described. 